In an increasingly networked world, digital networks are being used to deliver additional data services to end-users. End-users may receive video and audio streams over a network, such as a packet-based network. IPTV (Internet Protocol Television), for instance, is a system where a digital television signal may be delivered to subscribing consumers using the Internet Protocol (IP).
IPTV may be delivered using a multicasting technique. Multicast generally refers to the delivery of data to a group of destinations simultaneously. In multicasting, to conserve bandwidth, data may be transmitted once over each link of the network. Data may be replicated when the link to the destinations splits. In comparison with multicast, when “unicast” is used to deliver data to several recipients, multiple copies of the data may be sent over the same link, potentially wasting bandwidth. The bandwidth savings using multicasting may be significant.
Networks may use routers, switches, and other network devices for receiving and forwarding multicast data. Such a network device may receive a multicast packet through a port and may determine which port or ports to forward the packet. The network device may access a routing or forwarding table to determine on which port or ports it should forward a packet that it received.